1. Field
Rotary, internal combustion engines.
2. General Background and State of the Art
Internal combustion engines burn fuel in their combustion chambers in the presence of oxygen (usually from air). Burning generates high temperature and pressure gases, which expand and apply force against movable engine parts. Movement of the parts produce mechanical energy. Thus, an internal combustion engine converts potential chemical energy in the fuel into kinetic mechanical energy. Therefore, they provide the power for practical mechanical work to move vehicles and run pumps and other equipment.
Internal combustion engines fall into two principal categories, intermittent and continuous. Piston engines, either four-stroke and two-stroke, are the most common intermittent engines. Less common rotary engines also are intermittent. Continuous combustion engines include gas turbines and jet engines.
Internal combustion engines find their most common use in vehicles including cars, trucks, busses, airplanes and ships. The ratio of the potential chemical energy of the fuel (normally gasoline or diesel fuel) to the weight of the fuel is high. Consequently, internal combustion engines can travel long distance while carrying all their fuel.
Gasoline piston engines are among the least efficient internal combustion engine, only about 25%-30% efficient. Direct injection diesel engine may be about 40% efficient, at least at lower RPMs. Gas turbines are among the most efficient—approximately 60% efficient at high revolutions. However, gas turbines are inefficient at low revolutions. Because most land vehicle engines operate close to idle or well below maximum RPM, gas turbines usually are impractical for most land vehicles.
Rotary internal combustion engines surfaced in the early 1900s. See Hanley, U.S. Pat. No. 1,048,308 (1912). The Wankel rotary engine, which was developed beginning in the 1960s, became commercialized. See U.S. Pat. Nos. 2,938,505, 3,306,269, 3,373,723, 3,793,998, 3,855,977, 3,923,013 and 4,072,132. The Wankel engine is an internal combustion engine that uses a rotary design instead of reciprocating pistons to convert the energy of expanding combustion gases into rotating motion. Its four-stroke cycle takes place in a space between the inside of an oval-like epitrochoid-shaped housing and a rotor that is similar in shape to a Reuleaux triangle. The public often refers to the Wankel engine as the “rotary engine,” but rotary engines may have other constructions.
Internal combustion engines compress an air-fuel mixture in a combustion chamber and ignite the fuel by an electric spark or ultra high compression. The resulting combustion expands the gases to transform chemical energy into mechanical energy.
The combustion chamber in a gas turbine is between two sets of opposing fan blades. The fan blades compress the air mixture. When fuel is introduced and ignited, the combustion products expand against downstream fan blades causing the blades to rotate. The energy from the blade rotation drives the vehicle or other device.
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